From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivo Sieben Subject: Deterministic behavior for TTY serial Date: Tue, 17 Apr 2012 16:38:30 +0200 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Alan Cox , RT To: linux-serial@vger.kernel.org Return-path: Received: from mail-ob0-f174.google.com ([209.85.214.174]:64422 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755827Ab2DQOib (ORCPT ); Tue, 17 Apr 2012 10:38:31 -0400 Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello, We are currently using the TTY framework for serial communication. We are wondering if it is possible to give the TTY device in more deterministic behavior (as in "less locks & no sleeping") So in case of non blocking read/write behavior: - We want directly write data to the serial_core transmit buffer and return immediately. - Incoming data should be buffered, on a read data is read directly from that buffer and when no data available return immediately We have the idea that the default N_TTY line discipline introduces too much overhead & locking behavior what makes it less suitable for deterministic serial communication on a PREEMT_RT platform. Our first thought was that we need to use some kind of "raw" line discipline, that directly writes data to the serial_core transmit buffer, and buffers incoming data. But isn't such a line discipline already available? Or are we missing a option/flag for the N_TTY line discipline, that will achieve the same behavior? Regards, Ivo Sieben